The drugmaker needs a replacement for its biggest seller, the Adderall treatment for ADHD, which loses patent protection in two years. Buy scooping up New Rivers Pharmaceuticals, Shire will get Vyvanse, an ADHD pill that is up for FDA approval.

“This is an important and complementary acquisition that gives us full control of Vyvanse,” says Shire ceo Matt Emmens, in a statement this morning, adding that the deal will improve operating margins and “significantly enhance” earnings growth.

The two drugmakers have a development deal for Vyvanse, although the FDA hasn’t yet approved the ADHD treatment. Two approvable letters were sent while more data was sought for review. Shires hpoes to launch Vyvance in the second quarter.

Separately, Shire said fourth-quarter profit was $68.6 million, or 13 cents a share, compared with $69 million, or 13 cents, a year earlier. Revenue was $497 million.